Just make the cloaks purchasable at Nomad stations for the cost in materials to have built it.
Edit: Alley just informed me that it's not just about cloaks, it's the fuel to run them. In that regard I'd suggest that since Nomads originated the technology, duplicate the code for cloaks but make them designated Nomad Cloaks. As for fuel, make it no fuel but allow a certain time length based on cargo capacity.
As a side note, having MOX available in more places besides lawful only Bretonia and Rheinland really sucks. (and for unlawful/semi-lawful there is Kreuz but it's the ONLY place in the game to get MOX without being Bret/Rhein lawful friendly.)